
// Make newform 775.3.d.d in Magma, downloaded from the LMFDB on 05 June 2024.
// To make the character of type GrpDrchElt, type "MakeCharacter_775_d();"
// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_775_d_Hecke();"
// To make the coeffs of the qexp of the newform in the Hecke field type "qexpCoeffs();"
// To make the newform (type ModFrm), type "MakeNewformModFrm_775_3_d_d();".
// This may take a long time!  To see verbose output, uncomment the SetVerbose lines below.
// The precision argument determines an initial guess on how many Fourier coefficients to use.
// This guess is increased enough to uniquely determine the newform.
// To make the Hecke irreducible modular symbols subspace (type ModSym)
// containing the newform, type "MakeNewformModSym_775_3_d_d();".
// This may take a long time!  To see verbose output, uncomment the SetVerbose line below.
// The default sign is -1.  You can change this with the optional parameter "sign".
function ConvertToHeckeField(input: pass_field := false, Kf := [])
    if not pass_field then
        poly := [-1, -6, 0, 1];
        Kf := NumberField(Polynomial([elt : elt in poly]));
        AssignNames(~Kf, ["nu"]);
    end if;
    Rf_num := [[1, 0, 0], [0, 1, 0], [-4, 0, 1]];
    Rf_basisdens := [1, 1, 1];
    Rf_basisnums := ChangeUniverse([[z : z in elt] : elt in Rf_num], Kf);
    Rfbasis := [Rf_basisnums[i]/Rf_basisdens[i] : i in [1..Degree(Kf)]];
    inp_vec := Vector(Rfbasis)*ChangeRing(Transpose(Matrix([[elt : elt in row] : row in input])),Kf);
    return Eltseq(inp_vec);
end function;


// To make the character of type GrpDrchElt, type "MakeCharacter_775_d();"
function MakeCharacter_775_d()
    N := 775;
    order := 2;
    char_gens := [652, 251];
    v := [2, 1];
    // chi(gens[i]) = zeta^v[i]
    assert UnitGenerators(DirichletGroup(N)) eq char_gens;
    F := CyclotomicField(order);
    chi := DirichletCharacterFromValuesOnUnitGenerators(DirichletGroup(N,F),[F|F.1^e:e in v]);
    return MinimalBaseRingCharacter(chi);
end function;

// To make the character of type GrpDrchElt with Codomain the HeckeField, type "MakeCharacter_775_d_Hecke();"
function MakeCharacter_775_d_Hecke(Kf)
    N := 775;
    order := 2;
    char_gens := [652, 251];
    char_values := [[1, 0, 0], [-1, 0, 0]];
    assert UnitGenerators(DirichletGroup(N)) eq char_gens;
    values := ConvertToHeckeField(char_values : pass_field := true, Kf := Kf); // the value of chi on the gens as elements in the Hecke field
    F := Universe(values);// the Hecke field
    chi := DirichletCharacterFromValuesOnUnitGenerators(DirichletGroup(N,F),values);
    return chi;
end function;


function ExtendMultiplicatively(weight, aps, character)
    prec := NextPrime(NthPrime(#aps)) - 1; // we will able to figure out a_0 ... a_prec
    primes := PrimesUpTo(prec);
    prime_powers := primes;
    assert #primes eq #aps;
    log_prec := Floor(Log(prec)/Log(2)); // prec < 2^(log_prec+1)
    F := Universe(aps);
    FXY<X, Y> := PolynomialRing(F, 2);
    // 1/(1 - a_p T + p^(weight - 1) * char(p) T^2) = 1 + a_p T + a_{p^2} T^2 + ...
    R<T> := PowerSeriesRing(FXY : Precision := log_prec + 1);
    recursion := Coefficients(1/(1 - X*T + Y*T^2));
    coeffs := [F!0: i in [1..prec]];
    coeffs[1] := 1; //a_1
    for i := 1 to #primes do
        p := primes[i];
        coeffs[p] := aps[i];
        b := p^(weight - 1) * F!character(p);
        r := 2;
        p_power := p * p;
        //deals with powers of p
        while p_power le prec do
            Append(~prime_powers, p_power);
            coeffs[p_power] := Evaluate(recursion[r + 1], [aps[i], b]);
            p_power *:= p;
            r +:= 1;
        end while;    
    end for;
    Sort(~prime_powers);
    for pp in prime_powers do
        for k := 1 to Floor(prec/pp) do
            if GCD(k, pp) eq 1 then
                coeffs[pp*k] := coeffs[pp]*coeffs[k];
            end if;
        end for;
    end for;
    return coeffs;
end function;


function qexpCoeffs()
    // To make the coeffs of the qexp of the newform in the Hecke field type "qexpCoeffs();"
    weight := 3;
    raw_aps := [[0, 0, -1], [0, 0, 0], [0, 0, 0], [0, -5, 1], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, -11, 7], [0, 0, 0], [0, 0, 0], [-31, 0, 0], [0, 0, 0], [0, 21, -17], [0, 0, 0], [30, 0, 0], [0, 0, 0], [0, 21, 23], [0, 0, 0], [-10, 0, 0], [0, -51, 7], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, -5, 49], [0, 69, 7], [0, 35, 41], [0, -45, 49], [0, 29, 47], [0, 75, -31], [0, 0, 0], [138, 0, 0], [0, 0, 0], [0, 0, 0], [-198, 0, 0], [0, 0, 0], [0, 35, -79], [0, 115, 1], [0, 0, 0], [150, 0, 0], [0, 0, 0], [0, 0, 0], [0, 21, -97], [0, 35, 89], [0, 0, 0], [0, 0, 0], [0, -91, -73], [0, 0, 0], [-330, 0, 0], [0, 0, 0], [0, -165, 1], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, -45, -119], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 189, -73], [550, 0, 0], [-90, 0, 0], [0, -205, -31], [0, 141, 103], [0, 0, 0], [0, -45, 161], [0, 0, 0], [0, 0, 0], [0, 0, 0], [202, 0, 0], [0, 0, 0], [0, -171, -113], [0, 0, 0], [0, 235, -119], [-358, 0, 0], [0, 0, 0], [0, 0, 0], [0, -245, -71], [0, 0, 0], [0, 0, 0], [0, 261, -137], [0, 301, -17], [738, 0, 0], [0, 0, 0], [0, -59, 223], [0, 315, -71], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 315, 41], [0, -99, -217], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, -285, -119], [0, 0, 0], [-942, 0, 0], [0, 0, 0], [0, -371, 127], [0, 275, 161], [0, 0, 0], [0, 195, -271], [0, 0, 0], [0, 0, 0], [830, 0, 0], [0, 0, 0], [0, 315, -239], [0, 69, 287], [0, 0, 0], [-1090, 0, 0], [0, 0, 0], [750, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0], [-810, 0, 0], [0, 429, -193], [0, -91, -313], [0, 0, 0], [0, 0, 0], [0, 195, 289], [0, 221, -337], [0, -219, 343], [0, 0, 0], [0, 0, 0], [0, 355, -311], [0, -325, 329], [0, 0, 0], [0, 0, 0], [0, 469, 127], [0, 0, 0], [0, 0, 0], [0, -539, -17], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0], [-1478, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0], [-1422, 0, 0], [-1210, 0, 0], [270, 0, 0], [0, 0, 0], [0, 0, 0], [0, 395, -391], [0, 0, 0], [0, 0, 0], [0, -165, 449], [0, -85, -439], [0, 0, 0], [-1262, 0, 0], [0, 0, 0], [110, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0], [0, 0, 0], [-1158, 0, 0], [0, 435, 329], [0, 0, 0], [0, 0, 0], [0, 715, -119]];
    aps := ConvertToHeckeField(raw_aps);
    chi := MakeCharacter_775_d_Hecke(Universe(aps));
    return ExtendMultiplicatively(weight, aps, chi);
end function;


// To make the newform (type ModFrm), type "MakeNewformModFrm_775_3_d_d();".
// This may take a long time!  To see verbose output, uncomment the SetVerbose lines below.
// The precision argument determines an initial guess on how many Fourier coefficients to use.
// This guess is increased enough to uniquely determine the newform.
function MakeNewformModFrm_775_3_d_d(:prec:=3)
    chi := MakeCharacter_775_d();
    f_vec := qexpCoeffs();
    Kf := Universe(f_vec);
    // SetVerbose("ModularForms", true);
    // SetVerbose("ModularSymbols", true);
    S := CuspidalSubspace(ModularForms(chi, 3));
    S := BaseChange(S, Kf);
    maxprec := NextPrime(997) - 1;
    while true do
        trunc_vec := Vector(Kf, [0] cat [f_vec[i]: i in [1..prec]]);
        B := Basis(S, prec + 1);
        S_basismat := Matrix([AbsEltseq(g): g in B]);
        if Rank(S_basismat) eq Min(NumberOfRows(S_basismat), NumberOfColumns(S_basismat)) then
            S_basismat := ChangeRing(S_basismat,Kf);
            f_lincom := Solution(S_basismat,trunc_vec);
            f := &+[f_lincom[i]*Basis(S)[i] : i in [1..#Basis(S)]];
            return f;
        end if;
        error if prec eq maxprec, "Unable to distinguish newform within newspace";
        prec := Min(Ceiling(1.25 * prec), maxprec);
    end while;
end function;


// To make the Hecke irreducible modular symbols subspace (type ModSym)
// containing the newform, type "MakeNewformModSym_775_3_d_d();".
// This may take a long time!  To see verbose output, uncomment the SetVerbose line below.
// The default sign is -1.  You can change this with the optional parameter "sign".
function MakeNewformModSym_775_3_d_d( : sign := -1)
    R<x> := PolynomialRing(Rationals());
    chi := MakeCharacter_775_d();
    // SetVerbose("ModularSymbols", true);
    Snew := NewSubspace(CuspidalSubspace(ModularSymbols(chi,3,sign)));
    Vf := Kernel([<2,R![-15, -12, 0, 1]>,<3,R![0, 1]>],Snew);
    return Vf;
end function;